That looks like the setup. How do I tie the vent pipe back into the P-trap after I take the drum out ?The vent will transition to a galvanized pipe in the wall
you will need to cut the sheet rock behind the tub wall and remove the lead pipe
tie onto the galvanized pipe
cut the wall in the room behind the tub.
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I find it hard to believe they were still installing lead drum traps in new homes in 1960.I am not commenting on advice but whomever did that job looks like he earned his money. One of the finest lead jobs I have ever seen